The present invention relates to an elastic grinding element for form-true grinding or sanding having an abrasive surface covered with abrasive grit, wherein an elastic material comprises part of the volume of the grinding element. The invention also relates to a method for producing such a grinding element.
A known grinding element of the above-mentioned type is provided with a statistical distribution of abrasive grit embedded in an elastomer and, usually, a foamed binder. The individual abrasive grains in this known grinding element tend to escape the grinding pressure exerted by the workpiece being worked on by rotating and tilting movements permitted by their elastically yielding support. No noticeable machining output can be realized with such a grinding element. It is therefore used primarily for finishing work for which it is excellently suited.
An improvement in the above grinding element has been brought about in that rather than "individually" embedding the abrasive grain it is embedded in hard bound composites, that is conglomerates having a thickness of 3-5 mm. These conglomerates "float" in a spaced relationship in the elastic material. Due to the larger dimensions in the geometric configuration of the conglomerates, the abrasive grain cannot escape or tilt out of the way under the grinding pressure exerted by the workpiece. Such a grinding element has considerable advantages but is expensive to manufacture and is not suitable for grinding with oil-containing coolants since the elastomer employed as the elastic material begins to swell between the conglomerates. Even with pure water or fully synthetic coolants, the elastomer swells in the region of the finest grains due to the very slight abrasive work and thus low wear on the grinding elements.
In addition to grinding elements of the above type, where the elastic material is a component of the grinding element, it is also known to use a grinding belt where the necessary elasticity is obtained by means of a more or less resilient contact roller over which the grinding belt travels. In spite of considerable improvements made within recent years, grinding belts still have the drawback that their machining output decreases with increasing use and the resulting roughness height of the belt decreases considerably. For this reason, grinding belts cannot be used at all in some fields.
Grinding elements in the form of laminae, which have been known for a long time, do not have the specific drawbacks of grinding belts but again have a considerably lower machining output connected with considerably increased production, resulting in higher grinding costs.
Finally there are presently in use laminated leather or felt elements which are coated with a mixture of grit and glue, but these are difficult to manufacture, depend on climate and have other drawbacks.